1. Field
The present embodiments relate to a vibration generator.
2. Related Art
In the related art, a vibration generator that is mounted in a case, for example, of a controller of a game machine and transmits a vibration to an operator is disclosed in, for example, JP-A-2005-95740, which is described hereinafter with reference to FIGS. 9A and 9B.
In a vibration generator 50 disclosed in JP-A-2005-95740, an elastic member 52 of leaf spring is mounted at an upper plate 51a of a case 51 and supported by a fixing portion 52a of one end only, which is fixed at the upper plate 51a and a connecting portion 54 of the other end is fixed to a moving body 53 by adhesion.
A weight 58 and coils 55 are fixed onto the lower surface of the moving body 53. Magnets 56 are mounted along the side walls 51b of the case 51. A yoke 57 faces the magnets in the case 51.
In FIG. 9A, electric current does not flow in the coils 55, which are disposed between the yoke 57 and the magnet 56. A magnetic flux generated from the magnet 56 perpendicularly travels across the coil 55 to the yoke 57.
However, when electric current unidirectionally flows into the coil 55, an electromagnetic force is induced in the Z direction by the magnetic flux and electric current, which can drive the moving body 53 in the Z direction.
A switch 59 having a fixing contact and a driving contact 59b is mounted by the side of the moving body 53, and the fixing contact 59a is fixed onto a pedestal 60 and connected with one end of the coil 55 through a wire 61. The driving contact 59b is connected with a pulse generating circuit 63 (current supplying circuit) through a wire 62 and the pulse generating circuit 63 is connected with the other end of the coil 55.
In FIG. 9A, the switch 59 is in connection, in this embodiment when a signal is inputted from an input unit 64, electric current flows into the coil at the same time with the generation of a pulse voltage in a pulse generating circuit 63. As unidirectional electric current flows into the coil 55, an electromagnetic force F is induced in the Z direction by the magnetic flux and electric current, so that the moving body 53 moves in the Z direction. Due to the movement of the moving body 53, the driving contact 59b is pressed down in the Z direction, thereby maintaining the connection of the switch 59.
Alternatively, when electric current stops flowing by change in the pulse voltage generated in the pulse generating circuit 63, the electromagnetic force does not activate and the moving body 53 is moved in the opposite direction to the Z direction by the elastic force of the elastic member 52, thereby disconnecting the fixing contact 59a and driving contact 59b of the switch 59. When the switch 59 is in disconnection, a pulse voltage is generated in the pulse generating circuit 63 and electric current starts flowing to the coil 55 at the same time with the generation of pulse voltage, and an electromagnetic force F is induced in the Z direction and the moving body 53 moves in the Z direction. By repeating the above operations, in the vibration of the vibration generator 50, a resonance point P of resonance frequency appears, for example, near 40 Hz frequency as shown in FIG. 10, and the magnitude of the vibration is outputted as about 10 N.
The vibration of about 10 N outputted at the resonance point P creates a click vibration, which is sensible by an operator.
The vibration generator 50 may also be used as an acceleration sensor in which an electromotive force is induced at the coil 55 resulting from a vibration of the moving body 53 by a vibration applied to the case 51 from the outside when electric current does not flow into the coil 55.
An input/output device 70 utilizing the known vibration generator 50 is described hereinafter with reference to a controller, for example, of a game machine as shown in FIG. 11. The input/output device 70 for a game machine includes a case 71, which is composed of a base 72 and a pair of grips 73 extending in the same direction from the left and right side of the base 72, respectively, and can be gripped by an operator.
The base 72 and grips 73 are formed by a peripheral wall 71a, lower wall 71b, and an upper wall 71c and the inside of the input/output device 70 is hollow. A pair of switches 74 that is operated by an operator with fingers is provided on the upper wall 71c of the base 72.
The vibration generator 50 is mounted on the lower wall 71b in the grip 73 (the left one in the figure). The lower plate 51c of the vibration generator 50 is fixed onto the lower wall 71b of the grip 73 by adhesives such that the vibrator 53 can vibrate vertically, for example, in the direction of arrow A.
According to this configuration, as electric current flows into the coil 55 and the vibrator 53 vertically vibrates, the vibration is transmitted to the grip 73 and the left side and the grip 73 also vibrates vertically, for example, in the direction of arrow A.
In this embodiment, an operator senses the vibration through his/her left hand.
According to the above-mentioned known vibration generator 50, although a resonance point P of resonance frequency appears at a low frequency, for example, near 40 Hz as shown in FIG. 10 and a large vibration can be outputted at the resonance point P, as the frequency becomes far away from the resonance point P (that is, the vibrator vibrates at a high frequency), outputted vibrations become weak. Accordingly, the operator has difficulty sensing the vibrations at high frequencies.
In these embodiments, an electromotive force, when electric current does not flow, is large only within a narrow band near the resonance point P and weakened toward high frequencies, and thus the known vibration generator can not be used as an accelerator sensor. Accordingly, a vibration generator that generates large vibration in a wide range of frequency including at least two different resonance frequencies and generates a strong electromotive force in a wide frequency band using large vibrations in a wide range of frequency band including at least two resonance frequencies is desired.